History
Billy was born in Newark, New Jersey to a Chinese immigrant family. Billy's parents worked in New York City in various jobs, eventually becoming successful middle-class professionals. Billy was an excellent student into his middle school years. His success was only marred by a suicide attempt in middle school due to the pressure of needing to succeed at all times. The image of perfection was ruined when Billy's mutant abilities became apparent during his eighth grade year. When Professor Xavier met with his parents, Billy was essentially disowned by his family and transferred to Xavier's School for Gifted Youngsters as a ninth grader.

When the students were each assigned to squads, Billy was assigned to Colossus' "Ardents". Billy began to slack off in his academic studies but was still a good student. He began to train in his speedster abilities at this time.

In his senior year, Billy was forced to become a temporary member of Xavier's school's staff after The Travelers attacked and removed the remaining adult staff members. During this time, Billy was a member of the New X-Men. He helped defeat the several threats including a sentinel (later revealed to be activated by The Travelers), a Brood attack (sent by The Travelers), an incursion by the mutant terrorist Mystique and her Brotherhood of Mutants, and a future version of Danger. It was revealed during this time that his speedster abilities were really an outgrowth of advanced time control.

As a staff member at Academy X and member of the eXalts team, Billy helped confront Mystique's students at Academy M and the terrorist group The Purifiers.

Billy was engaged to Ruth Aldine (Blindfold) prior to her death. He was later able to gain enough control of his time manipulation abilities to go back in time and save her. They married shortly afterward.

When Meghan/Sinmara created a portal to Muspelheim, Billy prevented Dagan from being dragged through when it was closing, but he was dragged through instead. He is currently missing.

Powers
Billy can control the flow of time. He can slow down time around him, making him seem to move at super-speed. He can also perform routine tasks seemingly very quickly (while time is slowed for him). He has the ability to affect one other person with this ability, as well. He can harm others by striking a vulnerable area in rapid succession. It has been revealed that Billy is an Omega-level mutant, meaning that his potential for affecting time is still unreached. It is theorized that he may have the capacity for time travel and even more.